Avsc

Pure JavaScript implementation of the Avro specification.

Features

Blazingly fast and compact serialization! Typically faster than JSON with much smaller encodings.
All the Avro goodness and more: type inference, schema evolution, and remote procedure calls.
Support for serializing arbitrary JavaScript objects.
Unopinionated 64-bit integer compatibility.

Installation

$ npm install avsc

avsc is compatible with all versions of node.js since 0.11.

Documentation

Examples

Inside a node.js module, or using browserify:

const avro = require('avsc');

Encode and decode values from a known schema:

const type = avro.Type.forSchema({
  type: 'record',
  name: 'Pet',
  fields: [
    {
      name: 'kind',
      type: {type: 'enum', name: 'PetKind', symbols: ['CAT', 'DOG']}
    },
    {name: 'name', type: 'string'}
  ]
});

const buf = type.toBuffer({kind: 'CAT', name: 'Albert'}); // Encoded buffer.
const val = type.fromBuffer(buf); // = {kind: 'CAT', name: 'Albert'}

Infer a value's schema and encode similar values:

const type = avro.Type.forValue({
  city: 'Cambridge',
  zipCodes: ['02138', '02139'],
  visits: 2
});

// We can use `type` to encode any values with the same structure:
const bufs = [
  type.toBuffer({city: 'Seattle', zipCodes: ['98101'], visits: 3}),
  type.toBuffer({city: 'NYC', zipCodes: [], visits: 0})
];

Get a readable stream of decoded values from an Avro container file compressed using Snappy (see the BlockDecoder API for an example including checksum validation):

const snappy = require('snappy'); // Or your favorite Snappy library.
const codecs = {
  snappy: function (buf, cb) {
    // Avro appends checksums to compressed blocks, which we skip here.
    return snappy.uncompress(buf.slice(0, buf.length - 4), cb);
  }
};

avro.createFileDecoder('./values.avro', {codecs})
  .on('metadata', function (type) { /* `type` is the writer's type. */ })
  .on('data', function (val) { /* Do something with the decoded value. */ });

Implement a TCP server for an IDL-defined protocol:

// We first generate a protocol from its IDL specification.
const protocol = avro.readProtocol(`
  protocol LengthService {
    /** Endpoint which returns the length of the input string. */
    int stringLength(string str);
  }
`);

// We then create a corresponding server, implementing our endpoint.
const server = avro.Service.forProtocol(protocol)
  .createServer()
  .onStringLength(function (str, cb) { cb(null, str.length); });

// Finally, we use our server to respond to incoming TCP connections!
require('net').createServer()
  .on('connection', (con) => { server.createChannel(con); })
  .listen(24950);

Current Tags